I. Field of the Invention
The present invention relates generally to container filling apparatus and more particularly to an improved, multi-purpose nozzle for use in such apparatus.
II. Discussion of the Prior Art
In most systems in which the present invention finds use, product from a supply tank is made to flow through a filling valve which typically may be opened by the presence of a container to be filled in place relative to the filling spout. The flow may be by gravity or, alternatively, pressure may be applied in the supply tank, depending upon the viscosity or flow properties of the product to be dispensed. As the product flows into the container to be filled, the air in the container is displaced either through its open top or through a vent tube when sealed filling takes place. Any froth or foam, such as may be encountered when the product being filled is a liquid soap or the like, also rises through the vent tube and may be collected for return to the supply tank. Such container filling apparatus also commonly includes a control mechanism which is capable of sensing when the product in the container reaches a predetermined level for effecting a closure of the product valve so that no more of the liquid may flow into the container.
Typical of the prior art filling apparatus is then system disclosed in the Cox U.S. Pat. No. 3,905,404. Here, a concentric arrangement of a inner pressure sensing tube and an outer product tube is coupled to a supply tank and a fluidic control unit whereby as the product being injected into the container rises to the level of the open end of the pressure sensing tube, a noticeable pressure change takes place which is sensed by the fluidic control unit which then operates to close a valve to block the flow of product through the product tube.
The Manas U.S. Pat. No. 3,589,410 also describes a related prior art system having a filling nozzle comprising a concentric arrangement of an inner product tube and an outer overflow/pressure sensing tube and incorporating the so-called "no-bottle, no-fill" feature. That is to say, before the product valve can be opened to allow a flow from the supply tank through the product tube, a container to be filled must be disposed directly beneath the filling nozzle.
The closest prior art known to applicants is represented by an earlier design to the preferred embodiment described herein which had been placed in public use by the Doboy Packaging Machinery Division of the Nordson Corporation, the assignee of the presnt invention. That earlier arrangement included a product dispensing nozzle including three concentric tubes. Specifically, the innermost tube comprised the product dispensing tube while the one adjacent to it provided the venting action whereby air and foam could be drawn from the container during the filling operation. The third and outermost outermost concentric tube was associated with a pneumatic level sensor. That earlier device was weight activated and pneumatically shut off.
In arrangements where the filling nozzle includes three concentric tubes, it is necessary for rapid filling that the lumen of the product tube be of a sufficient size so that with practical pressures and the like, a desired flow rate can be maintained. This necessitates a larger diameter venting tube and still an even greater diameter pressure sensing tube. With three concentric tubes, relatively thin wall tubing is required if the composite probe is to fit within certain container openings. Thin wall tubing, of course, may be easily damaged if rigid containers are being filled and the container opening is not perfectly centered relative to the probe. The damage may lead to jamming or erratic level sensing which, of course, is to be avoided.